Serum Zinc Level in Children with Febrile Seizure.

Objectives
Febrile seizure (FS) is the most common type of seizure in children. FS is a genetic age-limited seizure, which only occurs with febrile illness. Today, it is known that genetic factors play a major role in the occurrence of FS. Nevertheless, some trace elements, such as zinc, may play an important role in the occurrence of FS. In this study, we investigated the serum level of zinc in patients with FS and febrile children without seizure (control group).


Materials &Methods
This prospective case-control study was conducted on 41 patients with simple and complex FS as the case group and 41 febrile children without seizure as the age- and sex-matched control group. The participants were admitted to Best Hospital of Hamadan, Iran between January 2013 and January 2014 . The children's age ranged from six months to five years. Serum zinc levels were measured by atomic absorption spectroscopy in these groups.


Results
The mean serum zinc levels were 70.41±20.46 and 92.73±17.62 mcg/dL in the case and control groups, respectively (P=0.001). The results showed that the serum zinc level in children with FS was significantly lower than that of the control group.


Conclusion
Based on the present results, serum zinc level was lower in children with febrile seizure. However, further basic research is needed to examine the efficacy of zinc supplements in the prevention of FS.


Introduction
Febrile seizure (FS), previously known as febrile convulsion, is the most common seizure in children (1,2). FS usually occurs between six months and five years of age (3). It is a genetic age-limited disorder, which only occurs with febrile illness (4). It is important to exclude central nervous system (CNS) infections and electrolyte imbalance before FS diagnosis. Also, patients should have no history of afebrile seizures (4,5). FS is classified into two simple and complex groups. Simple FS is generalized, lasts for 10-15 minutes, and occurs once in 24 hours. Conversely, complex FS is characterized by prolonged focal seizures, which occur more than once in 24 hours (5).
The main mechanism of FS pathophysiology is not clear yet (2,5). Today, it is known that genetic factors play a major role in the occurrence of FS, although some environmental factors, such as trace elements (e.g., zinc), may be involved in the association of genetic changes with FS occurrence (5,6). Generally, zinc is an important trace element, which contributes to growth and development, neurological function, nerve impulse transmission, and hormone release (7).
It also stimulates the activity of pyridoxal kinase, as the enzyme modulating the level of gamma aminobutyric acid (GABA) (8). In this prospective study, we evaluated zinc level in children withthe first FS attack and febrile children without seizure.
Our findings can help clinicians make a definite decision about the use of zinc supplements for preventing the recurrence of febrile seizures via regulation of some neurological functions (e.g., reducing neuronal excitability and affecting synaptic vesicles) (6,9).

Materials &Methods
This prospective case-control study was performed  there was no significant difference between these patients(P=0.804).  In the present study, the mean serum zinc level was 70.41±20.46 mcg/dL in the case group and 92.73±17.62 mcg/dL in the control group. There was a significant difference between the groups (P=0.001), although none of our participants were zinc-deficient (<40 mcg/dL). In a similar case-control study from Iran, Salehiomran et al. revealed that the mean serum level of zinc in FS patients was significantly lower than that of febrile children without seizure (58 vs. 71 mcg/dL) (11).
Moreover, in a previous case-control study, the mean serum level of zinc in children with FS was lower than that of controls; however, the difference was not statistically significant (52.8 vs. 56.1 mcg/ dL) (P=0.66) (13).
In another similar study, Heydarian et al. showed that the mean serum level of zinc was lower in patients with simple FS, compared to febrile age-matched children without seizure, and the difference was statistically significant (14). In another recent study, Lee et (19). Moreover, in the most recent study from Iran, researchers not only found no significant difference in the serum level of zinc between children with FS and healthy children, but also the mean serum level of zinc in the FS group was scarcely higher than that of the control group (20).
Finally, some limitations must be acknowledged in this study, such as the small sample size and lack of zinc level measurements in the cerebrospinal fluid.
Also, it is still unclear if lower zinc level in some febrile children is related to seizure occurrence.
In Conclusion, In this study, we found that the serum level of zinc in children with FS was lower than the control group (febrile children without seizure), and the difference was statistically significant. However, we cannot recommend zinc administration for prevention of FS, and further basic research is necessary in the future.